This invention relates to the manufacture of disposable containers or cups.
The term "cups" will be used throughout the specification, but the expression is intended to include other containers and hollow ware. The cups are principally intended for containing foodstuffs, for example, beverages and soups.
Known methods of producing disposable cups include the thermoforming of cups directly from a sheet or diaphragm of a plastics material and also the extrusion or injection of a parison of plastics material which is subsequently blow-molded to form the cup. such cups comprise a side wall, a base and an integral bottom wall projecting below and extending around the base of the cup. The bottom wall may be obtained by molding the cup with a side wall and a base, and raising the central portion of the base by means of a movable support piston, thus leaving a channel around the edge of the base, the walls of the channel forming a double bottom wall of the cup. As an alternative, the side wall and the base may be formed separately and welded together by a process of spin welding. A cup of this type is stronger at the base than the cup described at first, and also has no channel within the bottom wall in which space contamination may be lodged. However, the method of manufacture is considerably more complicated than the first-mentioned process.